324,596 research outputs found
Engines of Liberation - Additional Notes
No full textThese short notes supplement the discussion in Greenwood, Seshadri and Yorukoglu (2004) on time-use studies and female labor-force participation.
Tantalum pentoxide waveguide amplifier and laser for planar lightwave circuits
No full textA planar lightwave circuit (PLC) has been envisioned to provide a new generation of optical networks capable of delivering signal at high speed and bandwidth to the household. High index contrast (HIC) and optical gain in the same material system would substantially enhance integration of different optical devices in a small area and compensate for the losses in the system to realise low cost, dense multi-functional PLCs. This thesis investigates the use of tantala as a HIC material system for realising gain efficient Erbium doped waveguide amplifiers (EDWAs) and lasers to be used at 1.5µm wavelength, towards realising dense multi-functional PLCs.Slab waveguides were fabricated by magnetron sputter deposition under optimised conditions of a powder pressed, Er:Ta2O5 target onto an oxidized silicon substrate. Optimised sputtering process yielded a Er:Ta2O5 thin film with a refractive index of 2.105 @ 1550 nm and a maximum erbium lifetime of 2.3 ms. Single mode rib waveguides were designed and the fabricated using photolithography and argon ion beam milling. A maximum propagation loss of 0.65 ± 0.05 dB/cm at 1600 nm was measured, the peak erbium absorption and emission cross-section was determined to be 4.8 ± 0.2 x 10-21 cm2 and 4.4 ± 0.2 x 10-21 cm2 respectively.Numerical modeling of Er:Ta2O5 based EDWA predicted a maximum gain of 4 dB/cm at 200 mW pump power, in a 5.4cm long waveguide with an erbium concentration of 5.4 x 1020 ions/cm3. Gain measurements were performed on a 2.3cm long rib waveguide with a erbium concentration of 2.7 x 1020 ions/cm3, at a pump power of 200mW, and a net optical gain of 2.25dB/cm peaking at 1531.5 nm was measured in a 2µm wide waveguide. The pump threshold with respect to the launched pump power was measured to be as low as 4.5mW. The cavity was formed by affixing two mirrors at the end facets of the waveguides. Lasing was observed in a single longitudinal and transverse mode peaking between 1556 and 1560nm. The lasing threshold of 14mW with a slope efficiency of 0.3% was measured with respect to the launched power.Finally, a feasibility study for inscribing sub-micron grating structures on the Er:Ta2O5 waveguides were carried out using interferometric ablation. Gratings inscribed with 23 mJ/cm2 energy density and 1000 pulses yielded a maximum reflectivity of 11dB for TE polarisation at 1505nm. This feasibility study shows potential to realise integrated cavity line narrowed lasers and filters. Tantala has long been used for different photonic applications but gain at 1.5 μm is demonstrated for the first time. The results presented in the thesis demonstrate that tantala due to its HIC, net optical gain and other inherent properties that it possesses have the potential to realise low cost, compact PLCs for the short haul networks
Quantifying the impact of inventory holding cost and reactive capacity on an apparel manufacturers profitability
No full textThis paper was motivated by the operational problems faced by Northco, a school uniform manufacturer in the Northeastern United States. Northco was facing high working capital costs while also incurring high stockout and markdown costs. This paper models the impact of inventory holding cost and reactive capacity on Northco's targeted understocking and overstocking cost and offers a solution methodology for such problems. We quantify the impact of varying inventory carrying costs (and hence, high working capital costs) on stockout costs and the value of additional capacity. Our results illustrate that apparel manufacturers with high working capital costs, and hence high inventory carrying costs, should target higher stockout costs and achieve lower capacity utilization. The results presented have application beyond Northco because high working capital cost is endemic to many supply chains
Parallel Iterative Solvers and Preconditioners Using Approximate Hierarchical Methods (Extended Abstract)
No full text) Ananth Grama, Vipin Kumar, Ahmed Sameh Department of Computer Science, University of Minnesota Minneapolis, MN 55455 {ananth, kumar, sameh}@cs.umn.edu Abstract In this paper, we report results of the performance, convergence, and accuracy of a parallel GMRES solver for Boundary Element Methods. The solver uses a hierarchical approximate matrix-vector product based on a hybrid Barnes-Hut / Fast Multipole Method. We study the impact of various accuracy parameters on the convergence and show that with minimal loss in accuracy, our solver yields significant speedups. We demonstrate the excellent parallel efficiency and scalability of our solver. The combined speedups from approximation and parallelism represent an improvement of several orders in solution time. We also develop fast and paralellizable preconditioners for this problem. We report on the performance of an inner-outer scheme and a preconditioner based on truncated Green's function. Experimental results on a 256 processor ..
Health and Wealth in a Life Cycle Model
No full textThis paper presents a preliminary model of health investments over the life cycle. Health affects both longevity and provides flow utility. We analyze the interplay between consumption choices and investments in health by solving each household’s dynamic optimization problem to obtain predictions on health investments and consumption choices over the lifecycle. Our preliminary model does a good job of matching the distribution of medical expenses across households in the sample. We illustrate the scope of future model applications by examining the effects of a stylized Medicare program on patterns of wealth and mortality.
sj-jpg-2-fac-10.1177_27325016231203654 – Supplemental material for Extracorporeal Shockwave Therapy Improves Outcomes Following Secondary Alveolar Bone Grafting
No full textSupplemental material, sj-jpg-2-fac-10.1177_27325016231203654 for Extracorporeal Shockwave Therapy Improves Outcomes Following Secondary Alveolar Bone Grafting by Demetrius M. Coombs, Viren Patel, Nicholas Kochenour, Niyant Patel and Ananth S. Murthy in FACE</p
Er:Ta<sub>2</sub>O<sub>5</sub> waveguide optimization & spectroscopy
No full textThe optimization of erbium-doped Ta thin film waveguides deposited by magnetron sputtering is described. Background losses below 0.4dB/cm have been obtained before post-annealing. A broad photoluminescence spectrum centered at 1534nm is obtained, and the photoluminescence power and fluorescence lifetime increase with post-annealing, yielding promising results for compact amplifiers
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
sj-docx-1-fac-10.1177_27325016231203654 – Supplemental material for Extracorporeal Shockwave Therapy Improves Outcomes Following Secondary Alveolar Bone Grafting
No full textSupplemental material, sj-docx-1-fac-10.1177_27325016231203654 for Extracorporeal Shockwave Therapy Improves Outcomes Following Secondary Alveolar Bone Grafting by Demetrius M. Coombs, Viren Patel, Nicholas Kochenour, Niyant Patel and Ananth S. Murthy in FACE</p
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